February 2014

The new wide-body hangar for United Airlines at Dulles International Airport can house two wide-body aircraft for maintenance in a 90,000 SF, 100 ft-high hangar bay flanked by a maintenance shop and two story offices. Archer Western was also responsible for furnishing and installing all specialty aircraft maintenance equipment including pre-conditioned air and 400-cycle power equipment and associated underslab piping.

One of the major features of work includes the hangar bay foam fire protection system supplemented by two steel water storage tanks. High-expansion foam concentrates are flexible firefighting agents used in fighting Class A, Class B, and LNG (liquefied natural gas) fires. The foam concentrate expansion ratios range from 50:1 up to 1,000:1 which make it suitable for a variety of applications including aircraft hangars, flammable liquid storage areas, and LNG facilities. The United Wide Body Hangar at Dulles International Airport has 17 foam generators that create enough foam to fill 90,000 square feet of floor space up to 8' tall in under one minute.

This high expansion foam fire suppression system was tested and performed in accordance with NFPA 11 and as determined by the Airport Building Authorities and Fire Departments. The AWC Team had to run the system until the fire marshal was content with the floor coverage that the foam generators produced. Both the fire marshal and building code inspector needed to visually inspect that the foam covered all four corners of the hangar footprint. In the case of the United Hangar project, the floor was completely covered in approximately 45 seconds. During the project's foam test, AWC used nearly 330 gallons of foam concentrate along with 7,000 gallons of water to fill the hangar up to 8' above finished floor. As the foam was dumped, the manufacturer's representative monitored the flow rate, the operation of the fire pumps, and the consistency of the mixture of concentration to water.

In conjunction with United's environmental team, the foam - which is irritating to the skin and eyes -was first dissipated with water via fire extinguishing hose reels, slowly collected in vacuum trucks that ran throughout the hangar floor, and finally deposited into large condensing mobile tanks to allow the foam concentration to dissipate to allowable concentrations to be hauled off and disposed. The clean-up process lasted approximately eight hours after setting off the foam suppression system while the foam was allowed to dissipate for another two weeks within the mobile tanks before being hauled off.

Check out a video of the Foam Test inside the United Dulles Hangar here.